My roommate Ern recently introduced me to McSweeny's series of Open Letters To People Or Entities Who Are Unlikely To Respond. They are absolute genius. I can't believe I had never come across these before. The titles themselves are perhaps the best part; scroll down to the bottom of the current letter to read the list.
I read through several, and so far, my favorite is An Open Letter To Lifetime Television For Women.
I was also highly amused by An Open Letter To Shirley MacLaine From A Former 11-Year-Old Who Was Sent To Her Apartment By George McGovern's Presidential Campaign in 1972.
I did notice multiple people writing open letters to their cats, complaining about various feline transgressions. If I ever wrote an open letter, it would go something like this:
An Open Letter To People Who Write Open Letters To Their Cats
Dear Unhappy Cat Owners,
There's an easy solution to your problems. Don't own a cat.
It would be longer, though. And don't get all riled up, cat owners. I like cats. But there's a reason why no one has written an open letter to his or her dog.